Commitments and Contingencies - Additional Information (Detail) ¥ in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2016 CNY (¥)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 CNY (¥)	Dec. 31, 2014 CNY (¥)	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating leases, rental expenses	¥ 84,673	$ 12,195	¥ 49,892	¥ 30,461
Recognized liabilities related to unrecognized tax benefits	¥ 34,977		¥ 32,596		$ 5,038

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration